1. Field of the Invention
The present disclosure relates to a display device. More particularly, the disclosure relates to a liquid crystal display device that provides against display unevenness attributable to ion aggregates.
2. Description of the Related Art
Liquid crystal display devices are generally configured to have a thio-film transistor (TFT) substrate disposed opposite to a counter substrate with liquid crystal sandwiched therebetween, the TFT substrate typically having pixel electrodes and TFTs formed thereon in a matrix pattern. The display device forms an image suitably controlling the light transmittance of liquid crystal molecules per pixel.
Liquid crystal includes impurities that tend to be ionized. Ions move in a particular direction inside a display area of the device and are liable to be localized near the display area periphery. The localized ions reduce the resistance of the liquid crystal. An image displayed on the liquid crystal display area will have a black stain appearing at a location where the liquid crystal resistance is low.
JP-A-2014-142456 describes an organic electroluminescent (EL) display device in which upper transparent electrodes outside the display area are supplied with a cathode voltage via through-holes constituted by a two-layer structure made of a metal film and a transparent conductive film. JP-A-2014-206622 describes a configuration in which dummy electrodes formed outside the display area are impressed with a predetermined voltage to move ions out of the display area. JP-A-2009-265484 describes a configuration in which shielding electrodes are formed outside the display area on the side of the TFT substrate to protect the display area from being affected by a scanning voltage from scanning line leader lines formed in the periphery of the display area. JP-A-1996-328042 describes a configuration in which, with a scanning line driver circuit incorporated in a liquid crystal display panel, shielding electrodes are formed in a manner covering the scanning line driver circuit so as to shield the liquid crystal against a direct-current voltage from the scanning line driver circuit.